A389277 Primes p such that sigma(p+1) = sigma(p+2).

13, 4363, 33997, 162601, 230389, 289453, 949633, 1154173, 1642153, 3296863, 5003737, 7955491, 10118653, 10813423, 12673093, 28440043, 29097781, 34577833, 41171023, 50128033, 57453493, 67798663, 81166837, 86701393, 94682131, 97716517, 100600729, 184677601, 191710069

Offset

1,1

Links

Table of n, a(n) for n=1..29.

Example

33997 is a term because sigma(33997+1) = sigma(33997+2) = 51840.

Mathematica

Select[Prime[Range[10^6]], Equal @@ DivisorSigma[1, # + {1, 2}] &] (* Amiram Eldar, Sep 28 2025 *)

Crossrefs

Cf. A000040, A000203, A002961, A008333, A119705, A389278, A389279.

Sequence in context: A182348 A094316 A270068 * A174310 A362659 A057842

Adjacent sequences: A389274 A389275 A389276 * A389278 A389279 A389280

Keyword

nonn

Author

S. I. Dimitrov, Sep 28 2025

Status

approved